Method of surface sizing paper comprising surface sizing paper with 2-oxetanone ketene multimer sizing agent

ABSTRACT

A sizing agent for paper that is a 2-oxetanone ketene multimer which is not solid at 35° C., particularly a multimer mixture in which at least 25 weight percent of the hydrocarbon substituents contain irregularities such as branched alkyl groups or linear or branched alkenyl groups. Paper surface sized with the 2-oxetanone ketene multimer sizing agent and the method of surface sizing paper are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.08/192,570, filed Feb. 7, 1994, now U.S. Pat. No. 5,658,815.

FIELD OF THE INVENTION

This invention relates to paper sizing agents that have reactivefunctional groups that covalently bond to cellulose fiber andhydrophobic tails that are oriented away from the fiber, to papersurface sizing methods using such paper sizes and to surface sizedpaper.

BACKGROUND OF THE INVENTION

The amount of fine paper produced under alkaline conditions has beenincreasing rapidly, encouraged by cost savings, the ability to useprecipitated calcium carbonate (PCC), an increased demand for improvedpaper permanence and brightness, and an increased tendency to close thewet-end of the paper machine.

Current applications for fine paper require particular attention tosizing before conversion or end-use, such as high-speed photocopies,envelopes, forms bond including computer printer paper, and addingmachine paper. The most common sizing agents for fine paper made underalkaline conditions are alkenyl succinic anhydride (ASA) and alkylketene dimer (AKD). Both types of sizing agents have a reactivefunctional group that covalently bonds to cellulose fiber andhydrophobic tails that are oriented away from the fiber. The nature andorientation of these hydrophobic tails cause the fiber to repel water.

Commercial ASA-based sizing agents may be prepared by the reaction ofmaleic anhydride with an olefin (C₁₄ -C₁₈). Commercial AKD's, containingone β-lactone ring, are prepared by the dimerization of the alkylketenes made from two saturated, straight-chain fatty acid chlorides;the most widely used AKDs are prepared from palmitic and/or stearicacid. Other ketene dimers, such as the alkenyl based ketene dimer(Aquapel® 421 of Hercules Incorporated, Wilmington, Del., U.S.A.), havealso been used commercially.

Ketene multimers, containing more than one β-lactone ring, have beendisclosed as sizing agents for paper in Japanese Kokai 168991/89 and168992/89, both of which are incorporated herein by reference. Theketene multimers are said to show improved sizing compared to the ketenedimers previously used, when applied as an internal size incorporated inthe paper pulp slurry. The ketene multimers are prepared from a mixtureof mono- and dicarboxylic acids.

Although ASA and AKD sizing agents are commercially successful, theyhave disadvantages. Both types of sizing agents, particularly the AKDtype, have been associated with handling problems in the typicalhigh-speed conversion operations required for the current uses of finepaper made under alkaline conditions (referred to as alkaline finepaper). The problems include reduced operating speed in forms pressesand other converting machines, double feeds or jams in high-speedcopiers, and paper-welding and registration errors on printing andenvelope-folding equipment that operate at high speeds.

These problems are not normally associated with fine paper producedunder acid conditions (acid fine paper). The types of filler and filleraddition levels used to make alkaline fine paper differ significantlyfrom those used to make acid fine paper, and these can cause differencesin paper properties such as stiffness and coefficient of friction whichaffect paper handling. Alum addition levels in alkaline fine paper,which contribute to sheet conductivity and dissipation of static charge,also differ significantly from those used in acid fine paper. This isimportant because the electrical properties of paper affect its handlingperformance. Sodium chloride is often added to the surface of alkalinefine paper to improve its performance in end-use applications.

The typical problems encountered with the conversion and end-usehandling of alkaline fine paper involve:

1. Paper properties related to composition of the papermaking furnish;

2. Paper properties developed during paper formation; and

3. Problems related to sizing.

The paper properties affected by paper making under alkaline conditionsthat can affect converting and end-use performance include:

Curl

Variation In Coefficient Of Friction

Moisture Content

Moisture Profile

Stiffness

Dimensional Stability

MD/CD Strength Ratios

One such problem has been identified and measured as described in"Improving The Performance Of Alkaline Fine Paper On The IBM 3800 LaserPrinter," TAPPI Papermakers Conference Proceedings (1991), and in"Improving the Converting and End-Use Performance of Alkaline FinePaper," TAPPI Papermakers Conference Proceedings (1994), pages 155-163,the disclosures of which are incorporated herein by reference. Theproblem occurs when using an IBM 3800 high speed continuous forms laserprinter that does not have special modifications intended to facilitatehandling of alkaline fine paper. That commercially-significant laserprinter therefore can serve as an effective testing device for definingthe convertibility of various types of sized paper on state-of-the-artconverting equipment and its subsequent end-use performance. Inparticular, the phenomenon of "billowing" gives a measurable indicationof the extent of slippage on the IBM 3800 printer between the undrivenroll beyond the fuser and the driven roll above the stacker.

Such billowing involves a divergence of the paper path from the straightline between the rolls, which is two inches (5 cm) above the base plate,causing registration errors and dropped folds in the stacker. The rateof billowing during steady-state running time is measured as thebillowing height in inches above the straight paper path after 600seconds of running time and multiplied by 10,000.

Typical alkaline AKD sized fine paper using a size furnish of 2.2 lbs.per ton (1.1 kilogram per metric tonne (kg/mtonne)) of paper shows anunacceptable rate of billowing, typically of the order of 20 to 80inches of billowing per second×10,000 (51 to 203 cm/sec×10,000). Paperhandling rates on other high-speed converting machinery, such as aHamilton-Stevens continuous forms press or a Winkler & Dunnebier CHenvelope folder, also provide numerical measures of convertibility.

There is a need for alkaline fine paper that provides improved handlingperformance in typical converting and reprographic operations. At thesame time, the levels of sizing development need to be comparable tothat obtained with the current furnish levels of AKD or ASA for alkalinefine paper.

SUMMARY OF THE INVENTION

One aspect of the invention is a surface sizing agent which is a2-oxetanone ketene multimer that is not solid at a temperature of 35° C.

Another aspect of the invention is a method of sizing paper by surfacesizing paper with these 2-oxetanone ketene multimer sizing agents.

Yet another aspect of the invention is paper surface sized with these2-oxetanone ketene multimer sizing agents.

The method of this invention for making paper under alkaline conditionsexhibits levels of sizing comparable to or better than those obtainedwith current AKD and ASA sizing technology, and gives improved handlingperformance in typical end-use and converting operations.

As used herein, "percent" or "%" means, with respect to components oringredients of a compound, composition or mixture, the weight of thecomponent or ingredient based on the weight of the compound, compositionor mixture containing it, unless otherwise indicated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention includes a sizing agent that is a2-oxetanone-based multimer sizing agent (herein also referred to as2-oxetanone multimer sizing agent or 2-oxetanone ketene multimer sizingagent), that at 35° C. is not a solid (not substantially crystalline,semi-crystalline, or waxy solid; i.e., it flows on heating without heatof fusion); paper made under alkaline conditions and treated with asurface sizing treatment comprising such sizing agent; and a method ofmaking the sized paper using such sizing agent.

More preferably, the sizing agent according to the invention is a liquidat 25° C., or even at 20° C. (The references to "liquid" of course applyto the sizing agent per se and not to an emulsion or other combination.)

The invention comprises a 2-oxetanone-based ketene multimer sizing agenthaving irregularities in the chemical structure of its pendanthydrophobic constituents; i.e., the chemical structure containsirregularities such as carbon-to-carbon double bonds or branching in oneor more of the hydrocarbon chains. (Conventional alkyl ketene dimers areregular in that they have saturated straight-chain hydrocarbon chains).

The surface sizing agent of this invention is preferably a 2-oxetanoneketene multimer, or a mixture of such multimer compounds, having theformula (I) ##STR1## in which n is an integer of at least 1, preferably1 to about 20 and more preferably about 1 to about 8. (In the formula(I), when n is 0, such compound is termed a 2-oxetanone ketene dimer.)

Mixtures of the 2-oxetanone ketene multimers preferably contain regioisomers of such multimer compounds and preferably contain an average nof from about 1 to about 8 and more preferably from about 2 to about 6.Such mixtures of 2-oxetanone ketene multimers may also contain some2-oxetanone ketene dimer, i.e., n=0 in formula (I), as a consequence ofthe preparation method (described below) used to make the multimers.

R and R" are substantially hydrophobic in nature, are acyclic, arepreferably hydrocarbons of at least about 4 carbon atoms in length andmay be the same or different. R and R" are more preferably about C₁₀-C₂₀ and most preferably about C₁₄ -C₁₆.

R and R", which may be the same or different, are preferablyindependently selected from the group of straight (linear) or branchedalkyl or straight (linear) or branched alkenyl. R and R" are morepreferably linear alkenyl. Preferably not all R and R" substituents arestraight alkyl chains and preferably at least 25% by weight of thesizing agent comprises the 2-oxetanone structure in which at least oneof R and R" is not straight chain (linear) alkyl. R and R" areordinarily derived from a monocarboxylic acid reactant, e.g., fatty acidand preferably an unsaturated fatty acid, when the ketene multimer isprepared from reaction of a monoacid component with a diacid component,as described below.

R' may be a branched, straight chain, i.e., linear, or alicyclic, i.e.,cyclic-containing, hydrocarbon and is preferably a hydrocarbon of fromabout 1 to about 40 carbon atoms. R' may more preferably be selectedfrom about C₂ -C₁₂ and most preferably from C₄ -C₈ ; in such cases, R'is preferably a straight chain alkyl. Alternatively, R' may morepreferably be selected from about C₂₀ -C₄₀ and most preferably fromabout C₂₈ -C₃₂ ; R' is preferably branched or alicyclic for the morepreferred about C₂₀ -C₄₀ and most preferred about C₂₈ -C₃₂.

R' is ordinarily derived from a dicarboxylic acid reactant when theketene multimer is prepared from reaction of a monoacid component with adiacid component, as described below.

The 2-oxetanone ketene multimer is preferably a mixture of 2-oxetanoneketene multimers, particularly a mixture of 2-oxetanone ketene multimerswhere at least 25 weight percent of the mixture is multimers containinghydrocarbon substituents with irregularities that may be branched alkyl,linear alkenyl and branched alkenyl.

Alkaline sizing agents of the present invention, that give levels ofsizing comparable to those obtained with current AKD and ASA sizingtechnology and improved handling performance in typical end-use andconverting operations, have a reactive 2-oxetanone group and pendanthydrophobic hydrocarbon tails. In that respect, they resembletraditional AKD-based sizing agents, but unlike the saturated straightchains in the fatty acids used to prepare conventional solid alkylketene dimer based sizing agents, the hydrocarbon chain in one or bothof the fatty acid chlorides used to prepare this class of sizing agentscontain irregularities in the chemical structure of the pendanthydrocarbon chains, such as carbon-to-carbon double bonds and chainbranching. Due to the irregularities in the pendant hydrocarbon chains,these sizing agents are not solid, and preferably are liquid, at or nearroom temperature, i.e., about 25° C.

The 2-oxetanone multimer surface sizing agents of this invention may beformed from mixtures of a fatty acid and a dicarboxylic acid. Preferredfatty acids include oleic (octadecenoic), linoleic (octadecadienoic),palmitoleic (hexadecenoic), linolenic (octadecatrienoic), isostearic andmixtures of these and/or other fatty acids. Preferred commerciallyavailable fatty acids are Pamak®-1, Pamak®-131 or Pamolyn® 380 liquidfatty acids (fatty acid mixtures available from Hercules Incorporated,Wilmington, Del., U.S.A.) and comprising primarily oleic acid andlinoleic acid. Other fatty acids that may be used are the followingunsaturated fatty acids: dodecenoic, tetradecenoic (myristoleic),octadecadienoic (linolelaidic), eicosenoic (gadoleic), eicosatetraenoic(arachidonic), cis-13-docosenoic (erucic), trans-13-docosenoic(brassidic), and docosapentaenoic (clupanodonic) acids and mixtures ofsuch fatty acids.

More preferably, the 2-oxetanone ketene multimer sizing agent made fromthe foregoing types of fatty acids, i.e., containing irregularities suchas unsaturation or branching, is at least 25% of the sizing agent, morepreferably at least about 50% and most preferably at least about 70%.

Dicarboxylic acids that may be used to form the 2-oxetanone multimers ofthis invention include azelaic acid, sebacic acid and dodecanedioicacid, all of which are preferred. Dicarboxylic acids made by thedimerization of unsaturated (monocarboxylic) fatty acids may also beused where the resultant dicarboxylic acid is preferably a C₂₄ -C₄₄dicarboxylic acid, and more preferably a C₃₂ -C₃₆ dicarboxylic acid. Insituations where the dicarboxylic acid is a fatty acid dimer, thebranching and/or cyclic-structure of such fatty acid dimers should beunderstood to contribute to the irregularities present in the resultant2-oxetanone ketene multimer sizing agent.

The ketene multimers of this invention may be defined by the ratio offatty acid component to dicarboxylic acid component used to prepare theketene multimers. The length of a ketene multimer oligomer, i.e., thevalue of n in the formula noted above, is a function of the molar ratioof fatty acid to dicarboxylic acid used to form the multimer.

Such ketene multimers are ordinarily a mixture of ketene multimers, withdifferent chain lengths; some ketene dimer may also be present in themixture, as mentioned previously, although such ketene dimer isunnecessary in the present invention. The 2-oxetanone ketene multimersof this invention are preferably mixtures containing n averaging fromabout 1 to about 8 and more preferably from about 2 to about 6, with anaverage n of about 2 to about 4 being the most presently preferred. Theaverage value for n for a mixture of oxetanone ketene multimers may becalculated from molecular weights determined by size exclusionchromatography. Oxetanone ketene multimers having a specific n value,e.g., n=3, may be recovered or isolated from the ketene multimermixtures by conventional separation techniques.

The mole ratio of the fatty acid component to the dicarboxylic acidcomponent in the reaction mixture of such components used to form themultimers is preferably from about 4:1 to about 1:5, more preferablyfrom about 2.5:1 to about 1:4 and most preferably from about 1:1 toabout 1:3. Representative examples of such surface sizing agents include2-oxetanone multimers formed from a mixture of oleic acid and sebacicacid at a mole ratio of about 2.5:1, and 2-oxetanone multimers preparedfrom a mixture of Pamak®-1 fatty acid and azelaic acid at a mole ratioof about 2.5:1. Preferred examples are 2-oxetanone multimers preparedfrom mixtures of Pamak®-131 and azelaic acid having mole ratios of fromabout 1:1 to about 1:4.

For use as surface sizing agents for the more preferred alkaline finepaper, the mole ratio of the fatty acid component to the dicarboxylicacid component is preferably about 1:1 to about 1:5, more preferablyabout 1:1.5 to about 1:4, and most preferably about 1:2.

These surface sizing agents may be prepared by known procedures; see,e.g., Japanese Kokai 168991/89 and Japanese Kokai 168992/89, thedisclosures of which are incorporated herein by reference. In the firststep, acid chlorides from a mixture of fatty acid and dicarboxylic acidare formed, using phosphorous trichloride or another conventionalchlorination agent. In an alternative procedure, the acid chlorides maybe prepared separately or sequentially from the fatty acid component andthe dicarboxylic acid component. The acid chlorides in the reactionmixture are then dehydrochlorinated in the presence of triethylamine oranother suitable base, to form the 2-oxetanone ketene multimer mixture.Stable emulsions of these surface sizing agents can be prepared in thesame way as standard AKD emulsions.

The invention also comprises paper made under acid or alkalinepapermaking conditions, preferably the latter, and surface sized withthe 2-oxetanone-based ketene multimer sizing agent, that is, with aketene multimer sizing agent containing the 2-oxetanone functionality.

The paper surface sized according to the invention does not encountersignificant machine-feed problems on high speed converting machines orreprographic operations. Such problems are defined as significant in anyspecific conversion or reprographic application if they cause misfeeds,poor registration, or jams to a commercially unacceptable degree as willbe discussed below, or cause machine speed to be reduced.

Preferably the invention further comprises alkaline paper that issurface treated with the 2-oxetanone based sizing agent according to theinvention and contains a water soluble inorganic salt of an alkalimetal, preferably NaCl, as well as alum and precipitated calciumcarbonate (PCC). However, the paper of this invention will often be madewithout NaCl.

Preferably the surface sized paper according to the invention is capableof performing effectively in tests that measure its convertibility onstate-of-the-art converting equipment and its performance on high speedend-use machinery. In particular, the paper according to the invention,that can be made into a roll of continuous forms bond paper having abasis weight of from about 15 to 26 lbs./1300 ft² (6.8 to 11.8 kg/121m²), more specifically about 17 to 22 lbs./1300 ft² (7.7 to 10 kg/121m²), and that is surface sized at an addition rate of at least about0.05 pounds/ton (0.025 kg/mtonne), is capable of running on the IBMModel 3800 high speed, continuous-forms laser printer without causing arate of billowing in inches of increase per second×10,000 greater thanabout 10 to 20.

Further, the preferred surface sized paper according to the invention,that can be made into sheets of 81/2×11 inch (21.6 cm×27.9 cm)reprographic cut paper having a basis weight of about 15-26 lbs./1300ft² (6.8-11.8 kg/121 m²) and is surface sized at an addition rate of atleast about 0.05 pounds/ton (0.025 kg/mtonne), is capable of running ona high speed laser printer or copier without causing misfeeds or jams ata rate of 5 or more in 10,000.

The preferred paper according to the invention, having a basis weight ofabout 15-26 lbs./1300 ft² (6.8-11.8 kg/121 m²), also can be converted toa standard perforated continuous form on a Hamilton-Stevens continuousform press at a press speed of at least about 1775 feet per minute (541m/min).

The invention also comprises the process of converting the paperaccording to the invention to a standard perforated continuous form on acontinuous forms press at a press speed of from about 1300 to 2000 feetper minute (396 to 610 m/min).

A further process according to the invention comprises running 81/2×11inch (21.6 cm×27.9 cm) reprographic cut paper, having a basis weight ofabout 15-26 lbs./1300 ft² (6.8-11.8 kg/121 m²), on a high speed,continuous laser printer or copier without causing misfeeds or jams at arate of 5 or more in 10,000, preferably without causing misfeeds or jamsat a rate of 1 or more in 10,000. By comparison, paper sized withstandard AKD had a much higher rate of double feeds on an IBM 3825 highspeed copier (14 double feeds in 14,250 sheets). In conventionalcopy-machine operation, 10 double feeds in 10,000 sheets isunacceptable. A machine manufacturer considers more than 1 double feedin 10,000 sheets to be unacceptable.

Another process according to the invention comprises converting thepaper according to the invention into at least about 900 envelopes perminute, preferably at least about 1000 per minute.

The surface sized paper of this invention may be any fine paper gradethat ordinarily requires sizing. Such paper includes continuous formsbond paper, envelope-making paper, offset printing paper, inkjetprinting paper and adding machine paper, as well as converted products,such as copy paper and envelopes.

The surface sizing agent and method of this invention may also beemployed with any other types of paper, including paper made under acidor alkaline papermaking conditions and including without limitationnewsprint, paperboard such as liquid packaging paperboard, recycledliner paperboard, for example, and molded paper end-use applicationsthat require sizing, and other paper products. Such applications includegluing with water-based adhesives, ink jet printing and offset printing.

The present invention also relates to a method of sizing paper bysurface sizing paper with the 2-oxetanone ketene multimer sizing agentsof the invention.

The surface sizing agents of this invention are applied via knownsurface sizing procedures, being applied externally to the preformedpaper. Surface sizing ordinarily involves addition of the sizing agentat a size press on a paper machine, where the sizing agent is applied toor metered onto the surface of the paper. Alternatively, surface sizingmay be carried out by addition of the sizing agent at the calenderstack, or by spraying, or by other coating techniques. The surface sizedpaper is typically dried at elevated temperatures using known dryingtechniques.

The surface sizing agent of this invention is preferably applied to thesurface of paper being surface sized in an amount of at least about0.0025 wt %, based on the weight of the dry sized paper. Paper surfacesized with the 2-oxetanone ketene multimer sizing agent of thisinvention preferably has from about 0.0025 wt % to about 0.5 wt %, morepreferably, from about 0.005 wt % to about 0.2 wt % and most preferably,about 0.01 to about 0.1 wt % sizing agent present on the dry sizedpaper, based on the weight of the dry surface sized paper.

Water or any aqueous solution of size press additive may be used incombination with the sizing agent of this invention, when added at thesize press. Addition levels of starch in the size press may range from 0to about 100 kg/mtonne of dry sized paper. Size press starches suitablefor use with the sizing agent of this invention include ethylatedstarch, oxidized starch, ammonium persulfate converted starch, enzymeconverted starch, cationic starch and the like.

The addition of the 2-oxetanone ketene multimer sizing agent of thisinvention at the size press or via other means for surface sizing ofpaper provides satisfactory sizing performance without the need for aninternal sizing agent. However, internal sizing agents may be used ifdesired. In the event that an internal sizing agent is employed, theinternal size addition level for paper of this invention is preferablyat least about 0.05 kg/mtonne (0.005 wt %), more preferably at leastabout 0.25 kg/mtonne (0.025 wt %) and most preferably at least about 0.5kg/mtonne (0.05 wt %), all based on the weight of the dry sized paper.The internal sizing agent may be any conventional paper sizing agent andpreferred internal sizing agents include alkyl ketene dimer, alkylketene multimer, alkenyl ketene dimer, alkenyl ketene multimer, alkylsuccinic anhydride and alkenyl succinic anhydride.

The 2-oxetanone multimers of this invention are typically 2-10 timesmore efficient than commonly used surface paper sizing agents, e.g.,high molecular weight styrene/maleic anhydride copolymers.

Another factor favoring use of the ketene multimer surface sizing agentsof this invention is their high molecular weight. Lower molecular weightpaper sizing agents such as alkenyl succinic anhydride and alkyl ketenedimer sizing agents, when added as surface sizing agents in the sizepress, can result in toner adhesion problems in copy paper andunsatisfactory paper handling performance. The ketene multimers of thisinvention also avoid the hydrolysis problems associated with use of ASAas a surface paper sizing agent; ASA when hydrolyzed may form depositsor precipitates that can result in surface defects on the sized paper orthat can contaminate the paper machinery.

The invention will now be described with reference to the followingspecific, non-limiting examples.

Experimental Procedures I

Paper that was internally sized for evaluation on the IBM 3800 laserprinter was prepared on a pilot paper machine at Western MichiganUniversity.

To make a typical forms bond paper-making stock, the pulp furnish (threeparts Southern hardwood kraft pulp and one part Southern softwood kraftpulp) was refined to 425 ml Canadian Standard Freeness (C.S.F.) using adouble disk refiner. Prior to the addition of the filler to the pulpfurnish (10% medium particle-size precipitated calcium carbonate), thepH (7.8-8.0), alkalinity (150-200 p.p.m.), and hardness (100 p.p.m.) ofthe paper making stock were adjusted using the appropriate amounts of H₂SO₄, NaHCO₃ NaOH, and CaCl₂.

The 2-oxetanone sizing agents, including the multimers, were prepared bymethods used conventionally to prepare commercial alkyl ketene dimers(AKDs); i.e. acid chlorides from a mixture of fatty acid anddicarboxylic acid were formed, using a conventional chlorination agent,and the acid chlorides were dehydrochlorinated in the presence of asuitable base.

A general procedure for preparation of a 2-oxetanone ketene product on alaboratory scale from a monocarboxylic fatty acid and a dicarboxylicacid, such as azelaic acid or a fatty acid dimer acid, is as follows.The mole ratio of monocarboxylic fatty acid component to dicarboxylicacid component is selected depending on whether a predominance of ketenedimer or a predominance of ketene multimer is desired. For ketenemultimers with an average n of from about 1 to 6, a preferred mole ratioof monocarboxylic fatty acid to dicarboxylic acid is from about 1:1 to1:4.

The fatty acid component is introduced to a stirred reactor, blanketedwith nitrogen, and heated to about 70° C. The dicarboxylic acidcomponent, if a liquid, is added directly to the reactor with the fattyacid, or, if a solid, is added gradually with stirring, to form amixture of the two components. The two component mixture is thenchlorinated at a temperature of about 65°-70° C. with phosphoroustrichloride, by gradual introduction of the PCl₃ chlorination agent over15-30 minutes or more. After addition of the PCl₃, the chlorinatedreaction product is stirred for an additional 15 minutes and thenallowed to settle. Phosphorous acids that form as a byproduct of thechlorination reaction are drained from the bottom of the reactor andthen excess PCl₃ reactant is removed from the reaction product byevaporation under vacuum.

Confirmation that acid chlorides are formed in the reaction product madeby this procedure may be obtained by IR determination of the presence ofa characteristic acid chloride absorbance at 1800 cm⁻¹.

Dehydrochlorination of the acid chlorides to form the desired2-oxetanone ketene product is carried out in a reactor blanketed withnitrogen. About 1 part (by weight) triethylamine base, typicallyrepresenting a 5% molar excess of triethylamine, is added to about 2-7parts (by weight) 1,2-dichloropropane solvent in the reactor withstirring, and both are heated to a temperature of about 30°-40° C. About1-3 parts of acid chloride reaction product in about one-half of thatamount of 1,2-dichloropropane is added gradually to the reactor withstirring over about 40 minutes, while maintaining a temperature of about40°-45° C. Approximately two hours after the start of the addition ofthe acid chloride reaction product, completion of thedehydrochlorination reaction is confirmed with IR, and if thecharacteristic acid chloride absorbance is detected at 1800 cm⁻¹,additional triethylamine may be added as necessary to complete thedehydrochlorination reaction.

Upon completion of the dehydrochlorination reaction, the reactionmixture is filtered to remove byproduct triethylamine hydrochloridesalts formed during the dehydrochlorination reaction. Subsequently, the1,2-dichloropropane solvent is evaporated under vacuum, and additionaltriethylamine hydrochloride salts that precipitate are removed byfiltration. The recovered product is a mixture which containspredominantly 2-oxetanone ketene multimer or dimer, depending on thespecific molar ratios of fatty acid and dicarboxylic acid employed asthe initial reactants. For use as a sizing agent, an emulsion of the2-oxetanone ketene product is prepared.

The 2-oxetanone sizing agent emulsions, including the multimeremulsions, were prepared according to the disclosure of U.S. Pat. No.4,317,756, which is incorporated herein by reference, with particularreference to Example 5 of the patent.

A sizing agent emulsion of a ketene multimer (or dimer) may be preparedby admixing 880 parts of water, 60 parts of cationic corn starch and 10parts of sodium lignin sulfonate. The mixture is adjusted to pH of about3.5 with sulfuric acid. The resulting mixture is heated at 90°-95° C.for about one hour. Water is then added to the mixture in an amountsufficient to provide a mixture of 1750 parts (total weight). About 240parts of the ketene multimer (or dimer) is stirred into the mixturetogether with 2.4 parts of thiadiazine preservative. The resultingpremix (at 65° C.) is homogenized in one pass through an homogenizer at3000 p.s.i. The homogenized product is diluted with water to a ketenemultimer (or dimer) solids content within the range of about 6% to about30% to form a sizing agent emulsion; it should be understood that theprecise solids content of the sizing agent emulsion is not critical.

Wet-end additions of sizing agent, quaternary-amine-substituted cationicstarch (0.75%), alum (0.2%), and retention aid (0.025%) were made. Stocktemperature at the headbox and white water tray was controlled at 110°F. (43° C.).

The wet presses were set at 40 p.s.i. gauge (207 cm Hg). A dryer profilethat gave 1-2% moisture at the size press and 4-6% moisture at the reelwas used (77 ft/min (23 m/min)). Before the size press, the sizing levelwas measured on a sample of paper torn from the edge of the sheet, usingthe Hercules Size Test (HST). The Hercules Size Test (HST) is a standardtest in the industry for measuring the degree of sizing. This methodemploys an aqueous dye solution as the penetrant to permit opticaldetection of the liquid front as it moves through the sheet. Theapparatus determines the time required for the reflectance of the sheetsurface not in contact with the penetrant to drop to a predeterminedpercentage of its original reflectance. All HST testing data reportedmeasure the seconds to 80% reflection with 1% formic acid ink mixed withnaphthol green B dye (Hercules Test Ink #2) unless otherwise noted. Theuse of this formic acid ink is a more severe test than neutral ink andtends to give faster test times. High HST values are better than lowvalues. The amount of sizing desired depends upon the kind of paperbeing made and the system used to make it. "Natural aged HST" valueswere obtained seven days after the paper was sized.

Approximately 35 lbs./ton (17.5 kg/mtonne) of an oxidized corn starchand 1 lb./ton (0.5 kg/mtonne) of NaCl were added at the size press (130°F. (54° C.), pH 8). Calender pressure and reel moisture were adjusted toobtain a Sheffield smoothness of 150 flow units at the reel (Column #2,felt side up).

A 35-minute roll of paper from each paper making condition was collectedand converted on a commercial forms press to two boxes of standard81/2"×11" (21.6 cm×27.9 cm) forms. Samples were also collected beforeand after each 35 minute roll for natural aged size testing, basisweight (20 lbs./1300 ft² (9.1 kg/121 m²)), and smoothness testing.

The converted paper was allowed to equilibrate in the printer room forat least one day prior to evaluation. Each box of paper allowed a 10-14minute (220 ft/min (67 m/min)) evaluation on the IBM 3800 laser printer.All samples were tested in duplicate. A standard acid fine paper was runfor at least two minutes between each evaluation to reestablish initialmachine conditions.

The height of billowing in inches at the end of the run, and the rate atwhich billowing occurred ((inches of increase in billowing persecond)×10,000), were used to measure the effectiveness of eachapproach.

EXAMPLE 1

A number of sizing agents were tested as internal sizes for theireffects on the IBM 3800 laser printer runnability of adifficult-to-convert grade of alkaline fine paper. The aboveExperimental Procedures I were followed.

The rate of paper billowing on an IBM 3800 high speed printer was usedto evaluate the converting performance of each sample of paper, asdescribed above under Experimental Procedures I. A summary of theresults of this testing is given in Table 1.

Several 2-oxetanone based alkaline sizing agents are shown that give abetter balance of sizing and runnability on the IBM 3800 laser printer(for instance, less billowing at similar levels of sizing) than astandard alkyl ketene dimer (AKD) sizing agent used as a control forcomparative purposes. The standard AKD sizing agent was made from amixture of stearic and palmitic acids, by conventional methods. This isa conventional, standard sizing agent of the type that lacks anyirregularities, such as double bonds or branching, in its pendanthydrocarbon chains. The best balance of sizing and handling performancewas obtained with one of the following agents: a 2-oxetanone based dimersizing material made from a mixture of about 73% oleic acid, about 8%linoleic acid, and about 7% palmitoleic acid, the remainder being amixture of saturated and unsaturated fatty acids, available from HenkelCorporation's Emery Group (Gulph Mills, Pa., U.S.A.) under the nameEmersol™ NF (referred to herein for convenience along with similar sizesbased on oleic acid as an oleic acid size).

Another 2-oxetanone dimer sizing agent was prepared from Pamolyn® 380fatty acid, consisting primarily of oleic and linoleic acid andavailable from Hercules Incorporated, Wilmington, Del., U.S.A., and a2-oxetanone dimer sizing agent made from isostearic acid. All thesesizing agents were liquids at 25° C., and in particular, at equal sizinglevels, gave better converting performance on the IBM 3800 laser printerthan the control, a standard AKD sizing agent made from a mixture ofstearic and palmitic acids.

                  TABLE 1                                                         ______________________________________                                                    Addition                                                                      Level       Natural                                               Composition (lbs./ton   Aged HST Rate of                                      of Size     (kg/mtonne))                                                                              (sec.)   Billowing*                                   ______________________________________                                        Oleic Acid   1.5 (0.75) 122      1.6                                          Oleic Acid  2.2 (1.1)   212      15.1                                         Oleic Acid  3.0 (1.5)   265      29.4                                         Oleic Acid  4.0 (2.0)   331      55.5                                         Oleic Acid  2.2 (1.1)   62       1.6                                          (Pamolyn ® 380)                                                           Isostearic  2.2 (1.1)   176      1.5                                          Control (AKD)                                                                              1.5 (0.75) 162      23.8                                         Control (AKD)                                                                             2.2 (1.1)   320      55.0                                         ______________________________________                                         *Inches of billowing/sec. × 10,000.                                

EXAMPLE 2

Additional sizing agents were tested as internal sizes for their effectson IBM 3800 laser printer paper runnability in a second set ofexperiments, in which the Experimental Procedures I described above werefollowed.

A conventional AKD emulsion and an ASA emulsion were evaluated ascontrols. The AKD sizing agent was a standard AKD as described inExample 1, with the emulsion being prepared generally as described aboveunder Experimental Procedures I. The ASA emulsion was prepared asdescribed by Farley and Wasser in "The Sizing of Paper (SecondEdition)," "Sizing with Alkenyl Succinic Anhydride" page 51, (1989), thedisclosure of which is hereby incorporated by reference. The performanceparameters measured in these studies were natural aged sizing andrunnability on the IBM 3800 laser printer. A summary of the results ofthese evaluations is given in Table 2.

The materials tested gave a better balance of sizing and convertingperformance (less billowing at the same level of sizing) than either ofthe commercial ASA or AKD sizing agents used as controls. The bestbalance of sizing and handling performance was obtained with a2-oxetanone dimer size prepared from Pamak®-1 fatty acid (a mixturecomprised primarily of oleic and linoleic acid) and a 2-oxetanonemultimer prepared from a 2.5:1 mixture of oleic acid and sebacic acid,both prepared generally as described above under Experimental ProceduresI. Both sizing agents gave levels of sizing comparable to that obtainedwith the ASA and AKD controls. Both sizing agents gave paper with betterrunnability on the IBM 3800 laser printer than the paper sized witheither the ASA or AKD standards.

                  TABLE 2                                                         ______________________________________                                                    Addition                                                                      Level       Natural                                               Composition (lbs./ton   Aged HST Rate of                                      of Size     (kg/mtonne))                                                                              (sec.)   Billowing                                    ______________________________________                                        Oleic/Linoleic                                                                             1.5 (0.75) 34       <1.7                                         Oleic/Linoleic                                                                            2.2 (1.1)   203      <1.7                                         Oleic/Linoleic                                                                            3.0 (1.5)   193      <4.6                                         Oleic/Linoleic                                                                            4.0 (2.0)   250      17.5                                         Oleic/Sebacic                                                                              1.5 (0.75) 53       <10.4                                        Oleic/Sebacic                                                                             2.2 (1.1)   178      <1.7                                         Oleic/Sebacic                                                                             3.0 (1.5)   270      <3.4                                         Oleic/Sebacic                                                                             4.0 (2.0)   315      16.6                                         Control (AKD)                                                                              1.5 (0.75) 162      166                                          Control (AKD)                                                                             2.2 (1.1)   320      48                                           Control (ASA)                                                                              1.5 (0.75) 127      52                                           Control (ASA)                                                                             2.2 (1.1)   236      83                                           Control (ASA)                                                                             3.0 (1.5)   286      166                                          ______________________________________                                    

EXAMPLE 3

Two 2-oxetanone multimers prepared from mixtures of azelaic acid andoleic acid generally as described under Experimental Procedures I andwith mole ratios as shown in Table 3 and from mixtures of azelaic acidand oleic/linoleic fatty acid, were tested as internal sizes. Paper fortesting was prepared on the pilot paper machine using the conditionsdescribed in the Experimental Procedures I. A standard paper internallysized with a commercial AKD size dispersion, such as described inExample 1, was evaluated as a control. A summary of the results of theseinternal size evaluations is given in Table 3.

Both types of 2-oxetanone multimer gave levels of HST sizing similar tothose obtained with the standard AKD control. Both multimer sizes gavelower levels of billowing on the IBM 3800 laser printer than thecontrol.

                  TABLE 3                                                         ______________________________________                                                    Addition                                                                      Level       Natural                                               Composition (lbs./ton   Aged HST Rate of                                      of Size     (kg/mtonne))                                                                              (sec.)   Billowing                                    ______________________________________                                        Oleic/Azelaic                                                                             2.2 (1.1)   186      <1.2                                         2.5:1                                                                         Oleic/Azelaic                                                                               3 (1.5)   301      <2.2                                         2.5:1                                                                         Oleic/Azelaic                                                                             4 (2)       347      <2.3                                         2.5:1                                                                         Oleic/Linoleic:                                                                           2.2 (1.1)   160      <2.4                                         Azeiaic 2.5:1                                                                 Oleic/Linoleic:                                                                             3 (1.5)   254      <2.4                                         Azeiaic 2.5:1                                                                 Oleic/Linoleic:                                                                           4 (2)       287      <2.4                                         Azeiaic 2.5:1                                                                 Control     2.2 (1.1)   267      10                                           Control       3 (1.5)   359      23                                           ______________________________________                                    

EXAMPLE 4

A series of Pamak®-1 fatty acid:azelaic acid 2-oxetanone multimers withfatty acid to dicarboxylic acid ratios ranging from 1.5:1 to 3.5:1 wereevaluated as internal sizes in a fourth set of experiments. These2-oxetanone ketene multimers were prepared generally as described abovein Experimental Procedures I. Paper for testing was again prepared onthe pilot paper machine at Western Michigan University using theconditions described in the Experimental Procedures I. The performanceparameters measured in these studies were: natural aged sizingefficiency and runnability on the IBM 3800 laser printer. Standard AKDand ASA sized paper were evaluated as controls. A summary of the resultsof these evaluations is given in Table 4.

All of the Pamak®-1:azelaic acid 2-oxetanone multimers gave a betterbalance of sizing and IBM 3800 laser printer runnability than either ofthe commercial controls.

                  TABLE 4                                                         ______________________________________                                                    Addition                                                                      Level       Natural                                               Composition (lbs./ton   Aged HST Rate of                                      of Size     (kg/mtonne))                                                                              (sec.)   Billowing                                    ______________________________________                                        1.5:1       2.5 (1.2)   209      <5                                           1.5:1       4.5 (2.2)   339      <5                                           2.5:1       2.0 (1.0)   214      <5                                           2.5:1       3.5 (1.8)   312      <5                                           2.5:1       4.0 (2.0)   303      <5                                           3.5:1       2.5 (1.2)   312      <5                                           3.5:1       4.0 (2.0)   303      <5                                           Control (AKD)                                                                              1.5 (0.75) 255      <5                                           Control (AKD)                                                                             3.0 (1.5)   359      15                                           Control (ASA)                                                                             3.0 (1.5)   253      23                                           ______________________________________                                    

EXAMPLE 5

An evaluation as internal sizing agents of a 2-oxetanone ketene dimersize made from oleic acid (generally as described above underExperimental Procedures I), with a comparison to an AKD commercial sizemade from a mixture of palmitic and stearic acids (generally asdescribed in Example 1), was carried out on a high speed commercial finepaper machine (3000 ft/min (914 m/min), 20 tons (18.2 mtonnes) of paperproduced per hour, 15 lbs./1300 ft² (6.8 kg/121 m²)). A typical formsbond paper making stock similar to that used in the ExperimentalProcedures I was used. Addition levels of the two internal sizing agentswere adjusted to give comparable levels of HST sizing (20-30 seconds,85% reflectance, Hercules Test Ink #2). No deposits were observed on thepaper machine.

The paper produced under these conditions was then evaluated on a highspeed Hamilton continuous forms press. The Hamilton press converts paperto a standard perforated continuous form. Press speed was used as ameasure of performance. Two samples of the AKD control were testedbefore and after the evaluation of the paper sized with the oleic acidbased size. The results are shown in Table 5.

The paper sized with the oleic acid size clearly converted at asignificantly higher press speed than the paper sized with the AKDcontrol.

                  TABLE 5                                                         ______________________________________                                        Run #     Sizing Agent                                                                              Hamilton Press Speed                                    ______________________________________                                        1         AKD CONTROL 1740 f.p.m. (530 m/min)                                 2         AKD CONTROL 1740 f.p.m. (530 m/min)                                 3         OLEIC ACID  1800 f.p.m. (549 m/min)                                           2-OXETANONE                                                         4         OLEIC ACID  1775 f.p.m. (541 m/min)                                           2-OXETANONE                                                         5         AKD CONTROL 1730 f.p.m. (527 m/min)                                 6         AKD CONTROL 1725 f.p.m. (526 m/min)                                 ______________________________________                                    

EXAMPLE 6

An evaluation as internal sizing agents of oleic acid 2-oxetanone ketenedimer size (prepared generally as described above under ExperimentalProcedures I), with a comparison with an AKD commercial standard sizeprepared from a mixture of palmitic and stearic acid (generally asdescribed in Example 1) was carried out on a commercial paper machineproducing a xerographic grade of paper (3100 ft/min (945 m/min), 18lbs./1300 ft² (8.2 kg/921 m²)). As in Example 5, addition levels of eachsizing agent were adjusted to give comparable levels of HST sizing afternatural aging (100-200 seconds of HST sizing, 80% reflectance, HerculesTest Ink #2). No deposits were observed on the paper machine. The paperproduced with oleic acid 2-oxetanone size ran without any jams or doublefeeds on a high speed IBM 3825 sheet fed copier (no double feeds in14,250 sheets). Paper prepared with the AKD controls had a much higherrate of double feeds on the IBM 3825 (14 double feeds in 14,250 sheets).

EXAMPLE 7

A 2-oxetanone dimer sizing agent was prepared for evaluation as aninternal size from oleic acid by known methods, generally as describedabove under Experimental Procedures I. A sizing emulsion was thenprepared from the oleic acid-based size by known methods, generally asdescribed above under Experimental Procedures I. Copy paper internallysized with the oleic acid-based 2-oxetanone sizing emulsion was made ona commercial fine paper machine (3100 ft/min (945 m/min), 40 tons (36.4mtonnes) of paper produced per hour, 20 lbs./1300 ft² (9.1 kg/121 m²),100-. precipitated calcium carbonate, 1 lb. of sodium chloride/ton ofpaper (0.5 kg/mtonne) added at the size press). Copy paper sized with astandard AKD (prepared from a mixture of palmitic acid and stearic acidgenerally as described in Example 1) sizing emulsion was also made as acontrol. The addition level of each sizing agent was adjusted to give50-100 seconds of HST sizing (1.4 lbs. (0.7 kg/mtonne) of standardcommercial AKD, 1.9-2.1 lbs. (0.95-1.05 kg/mtonne) of oleic acid sizeper ton of paper, 80% reflectance, Hercules Test Ink #2).

The copy paper internally sized with oleic acid-based 2-oxetanone sizingagent ran without any jams or double feeds on a high speed IBM 3825sheet fed copier (no double feeds in 99,000 sheets). The paper sizedwith the AKD control had a much higher rate of double feeds on the IBM3825 (14 double feeds in 27,000 sheets).

EXAMPLE 8

Two samples of 2-oxetanone-based dimer sizing agents were prepared forevaluation as internal sizing agents respectively from oleic acid andPamak®-1 fatty acid by known methods, generally as described above underExperimental Procedures I. Sizing emulsions were prepared from bothsizes. Forms bond paper samples internally sized respectively with thePamak®-1 fatty acid-based dimer size and the oleic acid-based2-oxetanone dimer sizing agent were made on a commercial fine papermachine (approximately 3000 ft/min (914 m/min), 16 lbs./1300 ft² (7.3kg/121 m²), 5 lbs./ton (2.5 kg/mtonne) alum, 10 lbs./ton (5 kg/mtonne)quaternary amine substituted starch). Forms bond paper sized with acommercial AKD (prepared from a mixture of palmitic acid and stearicacid) sizing emulsion was also made as a control. The addition level ofeach sizing agent (See Table 6) was adjusted to give comparable levelsof HST sizing at the reel (70% reflectance, Hercules Test Ink #2).

The paper produced under these conditions was converted on a high speedHamilton continuous forms press. The Hamilton press converts paper to astandard perforated continuous form. Press speed was used as a measureof paper performance. The results are listed in the following Table 6.Each press speed is an average of measurements made on six differentrolls of paper. The paper sized with the oleic acid-based 2-oxetanonesize and the paper sized with the Pamak®-1 fatty acid-based 2-oxetanonesize converted at a significantly higher press speed than the papersized with the AKD control.

                  TABLE 6                                                         ______________________________________                                                                     HBT                                                     Sizing                Sizing  Hamilton                                 Run #  Agent      Add'n Level                                                                              (seconds)                                                                             Press Speed                              ______________________________________                                        1      AKD Control                                                                              2.0 lbs./Ton                                                                             208     1857 ft/min                                                (1 kg/mtonne)      (566 m/min)                              2      Oleic Acid-                                                                              2.5 lbs./Ton                                                                             183     1957 ft/min                                     based Size (1.25              (596 m/min)                                                kg/mtonne)                                                  1      PAMAK ®                                                                   2.5 lbs./Ton                                                                             185        1985 ft/min                                             Fatty Acid-                                                                              (1.25              (605 m/min)                                     based Size kg/mtonne)                                                  ______________________________________                                    

EXAMPLE 9

A 2-oxetanone-based dimer sizing agent was prepared from oleic acid byknown methods, generally as described above under ExperimentalProcedures I. A sizing emulsion was then prepared for evaluation as aninternal sizing agent from the oleic acid-based 2-oxetanone dimer sizingagent by known methods, generally as described above under ExperimentalProcedures I. Envelope paper internally sized with the oleic acid-basedsizing emulsion and containing 16% precipitated calcium carbonate wasmade on a commercial fine paper machine in two basis weights, 20 lbs.per 1300 ft² (9.1 kg/121 m²) and 24 lbs. per 1300 ft² (10.9 kg/121 m²).Envelope paper internally sized with a standard commercial AKD (preparedfrom a mixture of palmitic acid and stearic acid) and a commercialsurface sizing agent (0.5 lb./ton (0.25 kg/mtonne) Graphsize A) sizingemulsion was also made as a control. The addition level of each internalsizing agent was adjusted to give comparable levels of HST sizing at thereel (100-150 seconds, 80% reflectance, Hercules Test Ink #2).

The paper internally sized with each of the two sizing agents wasconverted to envelopes on a Winkler & Dunnebier CH envelope folder. The20-lb. (9.1 kg) paper was converted to "Church" envelopes. The 24-lb.(10.9 kg) paper was converted to standard #10 envelopes. Envelopeproduction rate (envelopes per minute) was used as a measure of paperconverting performance. The results are listed in the following Table 7.The paper sized with the oleic acid-based 2-oxetanone size converted ata significantly higher speed than the paper sized with the AKD control.

                  TABLE 7                                                         ______________________________________                                                                                Envelopes                             Sizing                                                                              Size Add'n HST      Basis         per                                   Agent Level      (sec.)   Weight Product                                                                              Minute                                ______________________________________                                        AKD   2.0        100-150  20 lbs.                                                                              Church 850                                   Control                                                                             lbs./Ton            (9.1 kg)                                                                             Envelope                                           (1 kg/mtonne)                                                           Oleic 2.9        100-150  20 lbs.                                                                              Church 900-950                               Acid- lbs./Ton            (9.1 kg)                                                                             Envelope                                     based (1.45                                                                   Size  kg/mtonne)                                                              AKD   1.5        100-150  24 lbs.                                                                              #10    965                                   Control                                                                             lbs./Ton            (10.9 kg)                                                                            Envelope                                           (0.75                                                                         kg/mtonne)                                                              Oleic 2.5        100-150  24 lbs.                                                                              #10    1000-                                 Acid- lbs./Ton            (10.9 kg)                                                                            Envelope                                                                             1015                                  based (1.25                                                                   Size  kg/mtonne)                                                              ______________________________________                                    

Experimental Procedures II

The papermaking procedures used to make paper for evaluation of surfacesizing, toner adhesion and inkjet quality were generally similar tothose described under Experimental Procedures I noted earlier. Paper wasagain prepared on the pilot paper machine at Western MichiganUniversity. The paper had a basis weight of 20 lbs./1300 ft² (9.1 kg/121m²).

To make a typical forms bond paper-making stock, the pulp furnish (threeparts hardwood kraft pulp and one part softwood kraft pulp) was refinedto 425 ml Canadian Standard Freeness (C.S.F.) using a double diskrefiner. Prior to the addition of the filler to the pulp furnish (12%medium particle-size precipitated calcium carbonate), the pH (7.8-8.0),alkalinity (150-200 p.p.m.), and hardness (100 p.p.m.) of the papermaking stock were adjusted using the appropriate amounts of H₂ SO₄,NaHCO₃, NaOH, and CaCl₂.

Wet-end conditions were as follows: tray pH 7.6-8.0; temperature 49° C.;and 180 ppm total alkalinity.

Wet-end additions were made as follows: precipitated calcium carbonatefiller (12%) at the first mixing box, quaternary-amine-substitutedcationic starch (0.50%) at the first mixing box outlet, alum (0.25%) atthe second mixing box outlet valve, and an internal sizing agent at thesecond mixing box valve.

The internal sizing agent added at the wet-end was acommercially-available alkenyl ketene dimer paper sizing agent, madefrom a fatty acid feedstock consisting primarily of oleic and linoleicacids, and this was utilized at three different usage levels, 0.1%,0.125% and 0.15%, all percentages being by weight based on the dryweight of the paper furnish. Stock temperature at the white water trayand head box was controlled at 49° C. (120° F.).

The wet presses were set at 40 p.s.i. gauge (207 cm Hg). A dryer profilethat gave 1-2% moisture at the size press and 4-6% moisture at the reelwas used (77 ft/min (23 m/min) paper machine speed). Before the sizepress, the sizing level was measured on a sample of paper torn from theedge of the sheet, using the Hercules Size Test (HST). With HerculesTest Ink #2, the reflectance was 80%.

Approximately 50 kg/metric tonne of an oxidized corn starch and 2.5kg/metric tonne of NaCl were added at the size press (66° C./150° F., pH8). The surface sizing agent was also added at the size press, inamounts as indicated in the Examples which follow. Calender pressure andreel moisture were adjusted to obtain a Sheffield smoothness of 150 flowunits at the reel (Column #2, felt side up).

EXAMPLE 10

This Example describes the preparation of a mixture of 2-oxetanonemultimer compounds from a mixture of fatty acids and a dicarboxylic acidat a mole ratio of 1:2 fatty acid to dicarboxylic acid. In Example 10A,the dicarboxylic acid was a C₃₆ dicarboxylic acid, and in Example 10B,the dicarboxylic acid was azelaic acid.

The chlorination of the fatty acid and dicarboxylic acid mixture wascarried out in a 500 mL glass-jacketed reactor fitted with a condenser,an addition funnel, and nitrogen adapters, which was sparged withnitrogen gas (each piece of glassware having been oven dried at 105° C.prior to assembly). The nitrogen gas flow was vented through a NaOHscrubber. The reactor was initially heated to 105° C. with a heat gunand cooled under a steady stream of nitrogen.

The dehydrochlorination of the acid chloride reaction product wascarried out in a 1 L glass-jacketed reactor fitted with a condenser, anaddition funnel, and nitrogen adapters, where was sparged with nitrogengas (each piece of glassware having been oven dried at 105° C. prior toassembly). The reactor was initially heated to 105° C. with a heat gunand cooled under a steady stream of nitrogen.

EXAMPLE 10A

The chlorination of the fatty acid and C₃₆. dicarboxylic acid wascarried out as follows. After the 500 mL reactor was cooled to roomtemperature, 87.8 g (0.31 mole) Pamak®-131 fatty acid mixture (HerculesIncorporated, Wilmington, Del., U.S.A.) and 353.1 g (0.62 mole)Unidyme®-14 C₃₆ dicarboxylic acid (Union Camp Corp., Wayne, N.J.,U.S.A.) were added to the reactor. At this point, the reactor was placedunder a static nitrogen blanket instead of a nitrogen gas sweep, i.e.,the nitrogen gas flow was stopped. The reactor containing the two liquidcomponents was then heated using a recirculating mineral oil bath set at70° C. After the temperature of the reactants had reached 65° C., 67.8mL PCl₃ (1.574 g/mL, B.P. 76° C., Aldrich Chemical Co., Inc., Milwaukee,Wis., U.S.A.) was loaded into the addition funnel and added to themixture over a period of 30 minutes. Vigorous evolution of HCl wasnoted, particularly at the beginning of the PCl₃ addition, but little orno exotherm was measured. Fifteen minutes after the addition of PCl₃ wascomplete, the stirrer was stopped. After ten minutes of settling, 29.9 gof phosphorous acids, a byproduct of the chorination reaction, weredrained from the bottom of the reactor. Small amounts of phosphorousacids were removed each hour over the next four hours, with a total of35.4 g phosphorous acids being removed. Finally, excess unreacted PCl₃was removed on a rotary evaporator (vacuum pump pressure, 60° C.) over a2-hour period. 453.7 g of acid chloride reaction product were isolated,a yield of 97.9%. An I.R. spectrum for the isolated reaction productshowed a characteristic acid chloride absorbance at 1800 cm⁻¹.

The dehydrochlorination reaction was carried out as follows. After the 1L reactor was cooled to room temperature, 440 mL 1,2-dichloropropanesolvent (1.156 g/mL, B.P. 95-96° C., Fluka Chemical Corp., Ronkonkoma,N.Y., U.S.A.) and 115.2 mL (0.83 mole) triethylamine (0.726 g/mL, B.P.88.8° C., Aldrich Chemical Co., Inc., Milwaukee, Wis., U.S.A.) wereadded to the reactor, the stirrer was started (150 r.p.m.) and thereactor contents were heated to 30° C. using a recirculating water bath.At this point, the nitrogen gas flow in the reactor was switched to anitrogen blanket. A 235.4 g aliquot of acid chloride reaction productwas then added to the addition funnel along with 110 mL1,2-dichloropropane. The contents of the addition funnel were graduallyadded to the reactor over a period of 40 minutes. Stirrer speed, thetemperature of the recirculating water bath, and the addition rate ofthe acid chloride reaction product were adjusted to control the exothermand maintain the temperature of the reaction mixture between 40°-45° C.The stirrer speed was gradually increased from 150 r.p.m. to 400 r.p.m.over the course of the addition. Two hours after the start of theaddition, the reaction was checked for acid chloride by I.R. Completionof the dehydrochlorination reaction is indicated when no acid chlorideabsorbance at 1800 cm⁻¹ is observed. Additional triethylamine may beadded to complete the reaction, as necessary.

Once the dehydrochlorination reaction was complete, the reaction mixturewas cooled to room temperature (about 25° C.) and filtered using aBuchner funnel to remove byproduct triethylamine hydrochloride saltsformed by the reaction. Approximately half of the 1,2-dichloropropanesolvent in the filtrate was then removed using a rotary evaporator(vacuum pump, 60° C.). The reaction product was filtered a second timeto remove additional triethylamine hydrochloride salts that hadprecipitated during evaporation of the 1,2-dichloropropane. Theremainder of the 1,2-dichloropropane was then removed on the rotaryevaporator (vacuum pump, 60° C., three hours). The reaction product wasthen filtered a third time to remove any remaining triethylaminehydrochloride salts. Total product yield was 137 g 2-oxetanone ketenemultimer product, a yield of 65%. The product was a liquid at 25° C.,and analysis by size exclusion chromatography indicated that the mixtureof ketene multimers had an average n of about 4.

EXAMPLE 10B

The chlorination of the fatty acid and azelaic dicarboxylic acid wascarried out as follows. After the 500 mL reactor was cooled to roomtemperature, 140.0 g (0.50 mole) Pamak®-131 fatty acid mixture (HerculesIncorporated, Wilmington, Del., U.S.A.) was added to the reactor andheated to a temperature of 70° C. At this point, the nitrogen gas flowin the reactor was switched to a nitrogen blanket. Next, 181 g (1.0mole) 85% azelaic acid mixture, containing 15%. other dicarboxylic acidsof different chain lengths (E-1110 from Henkel Corporation's EmeryGroup, Gulph Mills, Pa., U.S.A.), were gradually introduced into thereactor with vigorous stirring (250 r.p.m.) over a three minute period.The solid dicarboxylic acid component formed a coarse dispersion withthe liquid fatty acid component in the reactor, and the temperaturedropped about 10° C. during the addition. After the temperature of thereactants reached 70° C., 108 mL PCl₃ (1.574 g/mL, B.P. 76° C., AldrichChemical Co., Inc., Milwaukee, Wis., U.S.A.) was loaded into theaddition funnel and added to the mixture over a period of 30 minutes.Vigorous evolution of HCl was noted, particularly at the beginning ofthe PCl₃ addition, but little or no exotherm was measured. The disperseddicarboxylic acid component dissolved during addition of the PCl3.Fifteen minutes after the addition of PCl₃ was complete, the stirrer wasstopped. After ten minutes of settling, 70.8 g phosphorous acids, abyproduct of the chorination reaction, were drained from the bottom ofthe reactor. Small amounts of phosphorous acids were removed each hourover the next three hours, with a total of 71.9 g phosphorous acids(104% of theoretical) being removed. Finally, excess unreacted PCl₃ wasremoved on a rotary evaporator (vacuum pump pressure, 60° C.) over a2-hour period. 349.6 g of acid chloride reaction product was isolated, ayield of 93%. An I.R. spectrum for the isolated reaction product showeda characteristic acid chloride absorbance at 1800 cm⁻¹, with a smallside band being observed at 1710 cm⁻¹.

The dehydrochlorination reaction was carried out as follows. After the 1L reactor was cooled to room temperature, 500 mL 1,2-dichloropropanesolvent (1.156 g/mL, B.P. 95°-96° C., Fluka Chemical Corp., Ronkonkoma,N.Y., U.S.A.) and 286 mL (2.05 mole) triethylamine (0.726 g/mL, B.P.88.8° C., Aldrich Chemical Co., Inc., Milwaukee, Wis., U.S.A.) wereadded to the reactor, the stirrer was started (150 r.p.m.) and thereactor contents were heated to 40° C. using a recirculating water bath.At this point, the nitrogen gas flow was switched to a nitrogen blanket.A 280.8 g aliquot of acid chloride reaction product was then added tothe addition funnel along with 133 mL 1,2-dichloropropane. The contentsof the addition funnel were gradually added to the reactor over a periodof 40 minutes. Stirrer speed, the temperature of the recirculating waterbath, and the addition rate of the acid chloride reaction product wereadjusted to control the exotherm and maintain the temperature of thereaction mixture between 40°-45° C. The stirrer speed was graduallyincreased from 150 r.p.m. to 400 r.p.m. over the course of the addition.Two hours after the start of the addition, the reaction was checked foracid chloride by I.R. Completion of the dehydrochlorination reaction isindicated when no acid chloride absorbance at 1800 cm⁻¹ is observed,although acid anhydride absorbance at 1815 cm⁻¹ can complicate thismeasurement. Additional triethylamine may be added to complete thereaction, as necessary.

Once the dehydrochlorination reaction was complete, the reaction mixturewas cooled to room temperature (about 25° C.) and filtered using aBuchner funnel to remove byproduct triethylamine hydrochloride saltsformed by the reaction. The separated triethylamine salts werereslurried in 150 mL 1,2-dichloropropane at about 25° C. to extract anydehydrochlorinated reaction product trapped in the salts and filtered asecond time. The filtrates were combined, and approximately half of the1,2-dichloropropane solvent in the filtrate was then removed using arotary evaporator (vacuum pump, 60° C.). The reaction product wasfiltered again to remove additional triethylamine hydrochloride saltsthat had precipitated during evaporation of the 1,2-dichloropropane. Theremainder of the 1,2-dichloropropane was then removed on the rotaryevaporator (vacuum pump, 60° C., three hours). The total reactionproduct yield was 175 g 2-oxetanone ketene multimer product, a yield of82%. The product was a liquid at 25° C., and analysis by size exclusionchromatography indicated that the mixture of ketene multimers had anaverage n of about 4.

EXAMPLE 11

This Example describes the use of four ketene multimers of thisinvention as surface sizing agents.

The four ketene multimers were prepared from Pamak®-131 fatty acid andazelaic acid mixtures having the following molar ratios of fatty acidcomponent to dicarboxylic acid component: 2.5:1, 1:1, 1:2:1 and 1:4. Theprocedure used to make the ketene multimer mixtures was similar to thatdescribed in Example 10.

For comparison, two surface sizing agents were included as controls, atthree usage levels, as shown in Table 8 below: alkenyl ketene diner,made from a linoleic and oleic acid mixture (generally as describedabove under Experimental Procedures I), and styrene-maleic anhydridecopolymer.

The addition levels of the four ketene multimers in the size press were0.005, 0.015 and 0.025 wt %, based on the weight of the dry sized paper.

In addition to the surface sizing agents utilized in the size press, aninternal sizing agent was also used: alkenyl ketene dimer (as describedabove) was added at the wet end of the papermaking machine, at usagelevels of 0.1-0.15 wt %, based on the weight of dry sized paper.

The results of these surface sizing evaluations are summarized in Table8. Sizing efficiencies for the treated paper that are shown in the Tableare measured as Hercules Sizing Test results, taken at three points:prior to the size press, at the reel after the size press and afternatural aging for about seven days.

All four of the ketene multimers tested gave large increases in sizingat the reel, after the size press surface sizing treatment, over allusage levels evaluated.

Three of the ketene multimers (2.5:1, 1:1, 1:2 fatty acid: diacidratios) provided sizing differences, at a 0.005 wt % addition level,that were comparable to the alkenyl ketene dimer surface sizing agentcontrol (at 0.005 wt %) and the styrene/maleic anhydride copolymersurface sizing agent control (at 0.05 wt %). The same three ketenemultimers, at a 0.025 wt % usage level, provided sizing efficienciesthat were comparable to the alkenyl ketene dimer sizing agent control(at 0.025 wt %) and styrene/maleic anhydride copolymer sizing agent (at0.15 wt %). The ketene multimer with the 1:4 fatty acid to diacid ratioprovided smaller, but still significant, increases in sizing efficiencyat the reel.

The results for the first three ketene multimers (2.5:1, 1:1, 1:2 fattyacid (FA) to diacid (DA) ratios) indicated that at a given usage level,these ketene multimer surface sizing agents are 6-10 times moreeffective than a conventional surface sizing agent, the styrene/maleicanhydride copolymer, used as a control.

                                      TABLE 8                                     __________________________________________________________________________    SIZING AGENTS SIZING PROPERTY                                                 Size Press    HST:    HST:                                                                              INKJET QUALITY                                      Sizing Agent                                                                         AKD Internal                                                                         before  after    Black Ink                                      and Addition                                                                         Size Addition                                                                        size                                                                              HST:                                                                              aging 7                                                                           Black                                                                              Front                                                                              TONER                                     Level  Level  press                                                                             at reel                                                                           days                                                                              Ink Line                                                                           Optical                                                                            Toner                                     (wt %) (wt %) (sec)                                                                             (sec)                                                                             (sec)                                                                             Growth                                                                             Density                                                                            Adhesion                                  __________________________________________________________________________    none   0.1    22  3   2   9    1.09 0.40                                      styrene/maleic                                                                       0.1    19  15  10  9    1.13 0.32                                      anhydride                                                                     copolymer                                                                     0.05                                                                          alkenyl ketene                                                                       0.1    --  23  19  8    1.11 0.41                                      dimer                                                                         0.005                                                                         alkenyl ketene                                                                       0.1    --  18  14  8    1.11 --                                        multimer                                                                      2.5:1 FA:DA                                                                   0.005                                                                         alkenyl ketene                                                                       0.1    --  22  19  2    1.11 --                                        multimer                                                                      1:1 FA:DA                                                                     0.005                                                                         alkenyl ketene                                                                       0.1    13  18  17  8    1.12 0.42                                      multimer                                                                      1:2 FA:DA                                                                     0.005                                                                         alkenyl ketene                                                                       0.1    --  10  8   8    1.10 --                                        multimer                                                                      1:4 FA:DA                                                                     0.005                                                                         styrene/maleic                                                                       0.1    --  66  59  8    1.13 0.35                                      anhydride                                                                     copolymer                                                                     0.15                                                                          alkenyl ketene                                                                       0.1    --  54  39  7    1.15 0.48                                      dimer                                                                         0.025                                                                         alkenyl ketene                                                                       0.1    29  64  39  4    1.13 --                                        multimer                                                                      2.5:1 FA:DA                                                                   0.025                                                                         alkenyl ketene                                                                       0.1    --  68  39  7    1.14 --                                        multimer                                                                      1:1 FA:DA                                                                     0.025                                                                         alkenyl ketene                                                                       0.1    14  58  40  7    1.13 0.41                                      multimer                                                                      1:2 FA:DA                                                                     0.025                                                                         alkenyl ketene                                                                       0.1    --  40  20  6    1.10 --                                        multimer                                                                      1:4 FA:DA                                                                     0.025                                                                         none   0.1    20  7   4   8    1.10 0.43                                      none   0.15   131 59  56  6    1.23 0.48                                      styrene/maleic                                                                       0.15   --  82  90  5    1.25 0.44                                      anhydride                                                                     copolymer                                                                     0.05                                                                          alkenyl ketene                                                                       0.15   --  92  91  6    1.27 0.42                                      dimer                                                                         0.005                                                                         alkenyl ketene                                                                       0.15   104 85  81  5    1.23 --                                        multimer                                                                      2.5:1 FA:DA                                                                   0.005                                                                         alkenyl ketene                                                                       0.15   --  94  71  7    1.23 --                                        multimer                                                                      1:1 FA:DA                                                                     0.005                                                                         alkenyl ketene                                                                       0.15   110 92  64  7    1.21 0.41                                      multimer                                                                      1:2 FA:DA                                                                     0.005                                                                         alkenyl ketene                                                                       0.15   --  66  70  5    1.20 --                                        multimer                                                                      1:4 FA:DA                                                                     0.005                                                                         none   0.15   151 88  84  8    1.28 0.45                                      styrene/maleic                                                                       0.15   147 145 135 2    1.28 0.41                                      anhydride                                                                     copolymer                                                                     0.15                                                                          alkenyl ketene                                                                       0.15   133 141 133 5    1.32 0.42                                      dimer                                                                         0.025                                                                         alkenyl ketene                                                                       0.15   --  153 132 5    1.30 --                                        multimer                                                                      2.5:1 FA:DA                                                                   0.025                                                                         alkenyl ketene                                                                       0.15   123 172 140 5    1.31 --                                        multimer                                                                      1:1 FA:DA                                                                     0.025                                                                         alkenyl ketene                                                                       0.15   --  133 101 5    1.26 0.45                                      multimer                                                                      1:2 FA:DA                                                                     0.025                                                                         alkenyl ketene                                                                       0.15   132 111 99  6    1.25 --                                        muitimer                                                                      1:4 FA:DA                                                                     0.025                                                                         none   0.15   120 43  55  5    1.20 0.44                                      none   0.125  103 31  15  8    1.15 --                                        styrene/maleic                                                                       0.125  --  77  75  4    1.16 --                                        anhydride                                                                     copolymer                                                                     0.1                                                                           alkenyl ketene                                                                       0.125  --  72  63  7    1.17 --                                        dimer                                                                         0.015                                                                         alkenyl ketene                                                                       0.125  51  83  58  7    1.16 --                                        multimer                                                                      2.5:1 FA:DA                                                                   0.015                                                                         alkenyl ketene                                                                       0.125  --  83  73  8    1.21 --                                        multimer                                                                      1:1 FA:DA                                                                     0.015                                                                         alkenyl ketene                                                                       0.125  102 84  65  6    1.17 --                                        multimer                                                                      1:2 FA:DA                                                                     0.015                                                                         alkenyl ketene                                                                       0.125  --  58  56  6    1.16 --                                        multimer                                                                      1:4 FA:DA                                                                     0.015                                                                         none   0.125  87  14  16  7    1.13 --                                        __________________________________________________________________________

EXAMPLE 12

The surface sized paper produced with the four ketene multimers inExample 11 was evaluated for inkjet printing quality in this Example,using a Hewlett Packard Model 560° C. Deskjet® inkjet printer. Twoinkjet print quality characteristics were measured: black ink linegrowth and optical density of the printed black ink. Results aresummarized in Table 8 in the two columns under "INKJET QUALITY".

Black ink line growth was measured by visual evaluation of line growthby feathering or wicking, i.e., spreading of ink beyond the printed lineborders. Print samples were compared to ten samples, ranked as 1-10 with1 being the best and 10 being the worst quality. Results are summarizedin Table 8 above, under the column heading "Black Ink Line Growth".

At the lowest usage level of ketene multimer surface size, all fourketene multimers provided black ink line growth that was at leastcomparable to a paper with a conventional surface-sizing surface sizedat a substantially higher usage level with a styrene/maleic anhydridecopolymer surface sizing agent.

At the highest usage level, the ketene multimer surface size providedapproximateley equivalent black ink line growth as compared to theconventional surface size, but the latter was used at a significantlyhigher usage level than the ketene multimer size.

Black ink front optical density values were obtained by optical densitymeasurements of black ink printed onto the sized paper, suchmeasurements being made on the front, i.e., printed side of the paper.High optical density values are desirable since they indicate goodquality, dense black ink printing. The results, shown in the penultimatecolumn of Table 8, show that the ketene multimer surface sizes generallyprovide satisfactory black ink optical density values comparable to thestyrene/maleic anhydride copolymer surface sizing agent used atsignificantly higher usage levels, particularly at the higher internalsize levels used concurrently with the ketene multimer surface size.

The results shown in Table 8 indicate that the four ketene multimersurface sizing agents evaluated are cost effective replacements for aconventional polymeric surface sizing agent like styrene/maleicanhydride copolymer, for paper grades requiring good inkjet printingquality.

EXAMPLE 13

This Example evaluated photocopier toner adhesion on copy paper surfacesized with a ketene multimer sizing agent, added at the sizing press.

The ketene multimer was prepared from a reaction mixture containingPamak®-131 fatty acids and azelaic acid in a 1:2 mole ratio. Theprocedure used to prepare the ketene multimer was similar to thatdescribed in Example 10.

For comparison, two conventional surface sizes were also included in theevaluation. The first was paper sized with a styrene/maleic anhydridecopolymer sizing agent, added at the size press at two usage levels,0.05 and 0.15 wt %, based on the weight of the dry sized paper. Suchconventional polymeric sizing agents provide good toner adhesion andwere included in this Example as a performance benchmark.

The second surface size included for comparative purposes was papersurface sized with an alkenyl ketene dimer sizing agent, made from amixture of linoleic and oleic acids, the sizing agent being added at thesize press at two usage levels, 0.005 wt % and 0.025 wt %, based on theweight of the dry sized paper. Paper containing no surface size was alsoincluded in the evaluation.

An internal size, the alkenyl ketene dimer used as a surface size, wasalso included as a wet end additive in the papermaking process, at twousage levels, 0.1 wt % and 0.15 wt %, based on the weight of the drysized paper.

Toner adhesion on the sized paper was evaluated using an optical densitymethod that measured the difference in optical density between blacktoner photocopied onto the front of the (uncreased) paper and the sameblack photocopied toner with a crack formed by creasing the paper (byfolding and unfolding). Poor toner adhesion typically results information of a larger width crack at the crease; the difference in thetwo optical density measurements is therefore large. Low values for theoptical density difference indicate good toner adhesion.

Results are summarized in Table 8 above, where photocopier toneradhesion values are reported in the last column.

As expected, the polymeric (styrene/maleic acid copolymer) surface-sizedpaper provided good toner adhesion and the alkenyl ketene dimersurface-sized paper exhibited poorer toner adhesion. Increasing thelevel of internal size used in combination with the surface size tendedto result in reduced toner adhesion.

Use of the ketene multimer as a surface sizing agent resulted in mixedbut generally satisfactory toner adhesion, with very little differencein toner adhesion from that obtained with the untreated control.

Based on these results, ketene multimers are expected to be moreefficient sizing agents than traditional polymeric surface sizingagents, without the toner adhesion problems associated with traditionalketene dimer sizing agents.

It is not intended that the Examples given here should be construed tolimit the invention, but rather they are submitted to illustrate some ofthe specific embodiments of the invention. Various modifications andvariations of the present invention can be made without departing fromthe scope of the appended claims.

What is claimed is:
 1. A method of sizing paper which comprises surfacesizing paper with a sizing agent that is a 2-oxetanone ketene multimerthat is not solid at a temperature of 35° C.
 2. The method of claim 1wherein the sizing agent is a liquid at 35° C.
 3. The method of claim 1where the sizing agent comprises a mixture of 2-oxetanone ketenemultimers that is not solid at a temperature of 35° C.
 4. The method ofclaim 3 wherein at least 25 weight percent of the mixture comprises the2-oxetanone ketene multimers containing hydrocarbon substituents withirregularities, the hydrocarbon substituents with irregularities beingselected from the group consisting of branched alkyl, linear alkenyl andbranched alkenyl groups.
 5. The method of claim 1 wherein the2-oxetanone ketene multimer has the formula (I) ##STR2## in which n isan integer of at least 1; R and R" are independently acyclichydrocarbons of at least about 4 carbon atoms; andR' is a branched,linear or alicyclic hydrocarbon of about 1 to about 40 carbon atoms. 6.The method of claim 5 wherein, in the formula (I), n is an integer of 1to about
 20. 7. The method of claim 5 wherein, in the formula (I), n isan integer of 1 to about
 8. 8. The method of claim 5 wherein the sizingagent comprises a mixture of 2-oxetanone ketene multimers having theformula (I).
 9. The method of claim 8 wherein, in the mixture of2-oxetanone ketene multimers, the average n, in the formula (I), for themixture of multimers is about 1 to about
 8. 10. The method of claim 8wherein the sizing agent mixture contains about at least 25 weightpercent of 2-oxetanone ketene multimers in which irregularities arepresent in R or R" or both, where the irregularities are selected fromthe group consisting of branched alkyl, linear alkenyl and branchedalkenyl groups.
 11. The method of claim 8 which further comprisespreparing the mixture of 2-oxetanone ketene multimers from a mixture offatty acid and dicarboxylic acid in a mole ratio of from about 4:1 toabout 1:5 fatty acid to dicarboxylic acid.
 12. The method of claim 8which further comprises preparing the mixture of 2-oxetanone ketenemultimers from a mixture of fatty acid and dicarboxylic acid in a moleratio of from about 2.5:1 to about 1:4 fatty acid to dicarboxylic acid.13. The method of claim 8 which further comprises preparing the2-oxetanone ketene multimers from a mixture of fatty acid anddicarboxylic acid in a mole ratio of from 1:1.5 to 1:4 fatty acid todicarboxylic acid.
 14. The method of claim 8 which further comprisespreparing the mixture of 2-oxetanone ketene multimers from a mixture ofan unsaturated fatty acid mixture and a dicarboxylic acid.
 15. Themethod of claim 14 wherein the fatty acid is selected from the groupconsisting of oleic, linoleic, linolenic, palmitoleic, and mixturesthereof.
 16. The method of claim 14 wherein the dicarboxylic acid isselected from the group consisting of azelaic acid, sebacic acid,dodecanedioic acid and a fatty acid dimer acid.
 17. The method of claim5 wherein, in the formula (I), R and R" are independently branched alkylor linear alkyl or branched alkenyl or linear alkenyl.
 18. The method ofclaim 17 wherein, in the formula (I), R and R" have about 10 to about 20carbon atoms.
 19. The method of claim 5 wherein, in the formula (I), R'is selected from the group consisting of C₂ -C₁₂ hydrocarbon and C₂₀-C₄₀ hydrocarbon.
 20. The method of claim 19 wherein, in the formula(I), R' is a branched or alicyclic hydrocarbon having about 28 to about32 carbon atoms.
 21. The method of claim 19 wherein, in the formula (I),R' is a linear alkyl having about 4 to about 8 carbon atoms.
 22. Themethod of claim 5 wherein the 2-oxetanone ketene multimer is a liquid at25° C.
 23. The method of claim 1 which further comprises adding thesurface sizing agent to a size press in a papermaking process.
 24. Themethod of claim 23 which further comprises adding the surface sizingagent to the size press in an amount sufficient to provide at leastabout 0.0025 wt % sizing agent, based on the weight of dry sized paperproduced.
 25. The method of claim 1 which further comprises adding aninternal sizing agent to paper furnish from which the paper is made. 26.The method of claim 25 wherein the internal sizing agent is selectedfrom the group consisting of alkyl ketene dimer, alkyl ketene multimer,alkenyl ketene dimer, alkenyl ketene multimer, alkyl succinic anhydrideand alkenyl succinic anhydride.
 27. The method of claim 1 wherein the2-oxetanone ketene multimer is a liquid at 25° C.
 28. The method ofclaim 27 which further comprises preparing the 2-oxetanone ketenemultimers from a mixture of fatty acid and dicarboxylic acid in a moleratio of from 1:1.5 to 1:4 fatty acid to dicarboxylic acid.
 29. Themethod of claim 27 wherein at least 25 weight percent of the mixturecomprises the 2-oxetanone ketene multimers containing hydrocarbonsubstituents with irregularities, the hydrocarbon substituents withirregularities being selected from the group consisting of branchedalkyl, linear alkenyl and branched alkenyl groups.
 30. The method ofclaim 1 wherein the 2-oxetanone ketene multimer is a liquid at 20° C.31. The method of claim 1 which further comprises preparing the2-oxetanone ketene multimers from a mixture of fatty acid anddicarboxylic acid in a mole ratio of from about 1:1 to about 1:5 fattyacid to dicarboxylic acid.
 32. The method of claim 1 which furthercomprises preparing the 2-oxetanone ketene multimers from a mixture offatty acid and dicarboxylic acid in a mole ratio of from 1:1.5 to 1:4fatty acid to dicarboxylic acid.
 33. The method of claim 1 which furthercomprises preparing the 2-oxetanone ketene multimers from a mixture offatty acid and dicarboxylic acid in a mole ratio of about 1:2 fatty acidto dicarboxylic acid.